Inhibition and Retrieval of Facts in Young and Older Adults

Are the inhibitory and faciliatory effects during retrieval of semantically related items present in amnestic mild cognitive impairment?

Prefrontal functions subserve inhibition control for retrieval of semantically related items inducing forgetting 19 a-MCI patients and 29 controls underwent neuropsychological evaluation and retrieval-practice paradigm (RPP) to estimate baseline remember (BR), retrieval-induced facilitation (FAC) and retrieval-induced forgetting (RIF). A-MCI patients underwent also 3 T-MRI to assess relationship between regional grey matter (rGM) volumes and RPP indexes Behaviourally, RIF and FAC were both observed controls, while RIF only was observed in a-MCI patients. In patients but not in controls, RIF was associated with cognitive efficiency and FAC with memory performance. Patients showed also associations between BR and rGM volumes in the precuneus, no association was found between rGM volumes and RIF and FAC. A-MCI patients did not benefit from repeated practice during retrieval of studied items, which is likely due to their memory disorder. In contrast, patient cognitive efficiency would drive retrieval suppression of interfering stimuli.

Principal component analysis suggests multiple dimensions of memory inhibition that are differentially affected by age

Background

Cognitive inhibition is among the executive functions that decline early in the course of normal aging. Failures to be able to inhibit irrelevant information from memory may represent an essential factor of age-associated memory impairment. While a variety of elaborate behavioral tasks have been developed that presumably all index memory inhibition, the extent to which these different tasks measure the same underlying cognitive construct that declines with age has not been well explored.

Methods

In the current study, 100 and 75 cognitively healthy younger (n = 71; age = 30.7 ± 5.4 years, 56.7% female) and older (n = 104, age = 69.3 ± 5.9 years, 66.2% female) adults with equivalent educational attainment performed three computer-based memory inhibition tasks: the Retrieval Induced Forgetting task, the Suppress task, and the Directed Forgetting task. We conducted a principal component analysis using scores derived from different components of these tasks to explore whether and how the tasks relate to one another. We further investigated how age, sex and education, along with, in a subsample of the participants, a neuropsychological measure of episodic memory, impacted both the task scores individually, and the principal components derived from the exploratory analysis.

Results

We identified 3 distinct sources of variability which represent potentially independent cognitive processes: memory retrieval facilitation, and two memory inhibition processes that distinguished themselves by the degree of volitional initiation of memory suppression. Only the memory retrieval component correlated with a neuropsychologically-derived episodic memory score, and both memory inhibition principal components were age dependent.

Conclusion

Our findings provide support for a distinction in memory suppression processes between those 'instructed' to be performed and those which happen without explicit instruction. This distinction adds nuance to the dichotomous classification of controlled vs. automatic inhibitory mechanisms, which have been shown in previous work to vary as a function of the degree of frontal involvement. Our findings further demonstrate that while both of these measures of inhibition were affected by age, the episodic memory component was not, suggesting that inhibitory impairments may precede memory deficits in healthy aging.

Retrieval-practice task affects relationship between working memory capacity and retrieval-induced forgetting

Retrieving a subset of items from memory can cause forgetting of other items in memory, a phenomenon referred to as retrieval-induced forgetting (RIF). Individuals who exhibit greater amounts of RIF have been shown to also exhibit superior working memory capacity (WMC) and faster stop-signal reaction times (SSRTs), results which have been interpreted as suggesting that RIF reflects an inhibitory process that is mediated by the processes of executive control. Across four experiments, we sought to further elucidate this issue by manipulating the way in which participants retrieved items during retrieval practice and examining how the resulting effects of forgetting correlated with WMC (Experiments 1-3) and SSRT (Experiment 4). Significant correlations were observed when participants retrieved items from an earlier study phase (within-list retrieval practice), but not when participants generated items from semantic memory (extra-list retrieval practice). These results provide important new insight into the role of executive-control processes in RIF.

False memories in Lewy-body disease

Recently, de Boysson, Belleville, Phillips et al. (2011) found that patients with Lewy-body disease (LBD) showed significantly lower rates of false memories than healthy controls, using the Deese-Roediger-McDermott (DRM) experimental procedure. Given that this result could be explained by the practically null rate of true recognition in the LBD group (0.09), we decided to replicate the study by de Boysson et al. (2011), but including a new condition that would maximize the true recognition rate (and analyze its effect on the rate of false memories). Specifically, in a DRM experiment, we manipulated (within subjects) two study and recognition conditions: in the "immediate" condition, both the LBD patients and the control group of healthy older people received a different recognition test after each study list (containing twelve words associated with a non-presented critical word), while in the "delayed" condition (similar to the one in de Boysson et al., 2011), the participants received the entire series of study lists and then took only one recognition test. The results showed that, in both samples, the "immediate" condition produced higher corrected rates of both true and false recognition than the "delayed" condition, although they were both lower in the LBD patients, which shows that these patients are capable of encoding and recognizing the general similitude underlying information (gist memory) in the right conditions.

Face naming and retrieval inhibition in old and very old age

BACKGROUND/STUDY CONTEXT: Aging has traditionally been related to impairments in proper name retrieval. This study analyzed the possible role of the Inhibitory Deficit Hypothesis in explaining face naming impairments during aging. The dynamics of inhibition have been thoroughly studied by the retrieval-practice paradigm (Anderson, Bjork, & Bjork, 1994, Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1063-1087) and its aftereffect, the retrieval-induced forgetting effect.

METHODS

A version of the retrieval-practice paradigm was employed: younger-old (YO; mean age = 66.40, SD = 3.94) and older-old (OO; mean age = 80.94, SD = 4.53) adults were asked to repeatedly name faces of categorically related famous people.

RESULTS

Retrieval-induced forgetting for names was observed in the YO group but not in the OO group.

CONCLUSION

These findings indicate that whereas the YO adults had enough resources to inhibit intrusive names, OO adults were not able to suppress competing names, supporting the proposal of the Inhibitory Deficit Hypothesis at older ages.

Low involvement of preexisting associations makes retrieval-induced forgetting long lasting

Research has shown that selective retrieval of episodic memories usually leads to forgetting of related memories that compete for retrieval [a phenomenon known as retrieval-induced forgetting (RIF)]. However, there are conflicting data regarding the duration of this incidental kind of forgetting. While some studies have found that this forgetting effect disappears within 24 h after selective retrieval, others suggest that it may last for as long as at least a week. In two experiments, we explored whether discrepancies in the durability of RIF may be due to variations in the type of relationships (preexisting vs. novel) that are present between items associated with a given cue. We explored this issue by manipulating the degree of involvement of preexisting/novel associations among competing items as well as the delay between retrieval practice and test (immediate in Experiment 1 and 24-h delay test in Experiment 2). The results suggest that forgetting lasts longer when the degree of preexisting associations among targets and competitors is low.

The role of warnings in younger and older adults' retrieval-induced forgetting

Retrieval-induced forgetting (RIF) is a phenomenon wherein practicing recalling some items impairs recall of semantically related, unpracticed items. Two experiments examined whether explicitly warning older (Experiment 1) and younger adults (Experiments 1 and 2) about RIF at different times during two exposures to the retrieval-practice paradigm would affect participants' forgetting. Participants in both experiments were either warned before encoding, retrieval-practice, recall, or not at all. The warning was combined with integration instructions in Experiment 2. Warnings did not reduce forgetting in either age group in Experiment 1. Forgetting increased across exposures in most cases and older adults experienced more forgetting than did younger adults. Combining integration instructions with the warning also did not reduce younger adults' forgetting relative to baseline conditions in Experiment 2. Results indicate that both younger and older adults are susceptible to retrieval-induced forgetting and that raising awareness of the phenomenon increases rather than decreases forgetting rates.

Forgetting in context: the effects of age, emotion, and social factors on retrieval-induced forgetting

Retrieval-induced forgetting (RIF) refers to the finding that selectively retrieving some information impairs subsequent memory for related but nonretrieved information. This occurs both for the individual doing the remembering (i.e., within-individual retrieval-induced forgetting: WI-RIF), as well as for individuals merely listening to those recollections (i.e., socially shared retrieval-induced forgetting: SS-RIF). In the present study, we examined how the contextual factors of age and emotion independently and interactively affect both WI-RIF and SS-RIF. The results indicated that both WI-RIF and SS-RIF occurred at equivalent levels, both for younger and older adults and for neutral and emotional information. However, we identified a boundary condition to this effect: People only exhibited SS-RIF when the speaker that they were listening to was of the same sex as themselves. Given that participants reported feeling closer to same-sex speakers, this suggests that people co-retrieve more, and therefore exhibit increased SS-RIF, with close others. In everyday life, these RIF effects should influence what information is remembered versus forgotten in individual and collective memories.

Part set cuing in older adults: further evidence of intact forgetting in aging

The aim of this study was to look at the effect of aging on part set cuing while equating for baseline performance in episodic memory. Younger and older participants listened to three different word lists, each containing 24 words relating to a particular category. During recall, 0, 33, or 66% of the items presented in the learning phase were re-presented as cues. The results showed that recall of the never cued items was equally impaired by the presence of cues in younger and older adults, thus showing equivalent part set cuing effects in both groups. These results parallel previous findings showing equivalent inhibitory effects in younger and older adults with tasks that do not require executive control and provide additional support to previous studies challenging the view that frontal/executive processes play a major role in part set cuing.